Zach Ertz is coming off a rookie season in which he caught 36 passes for 469 yards and four touchdowns. (AP)

FOXBOROUGH, Mass. — If anyone is qualified to make an expert judgment on tight ends, it’s Patriots linebackers and defensive backs, and both agree Eagles tight end Zach Ertz is primed for a breakout season.

The Patriots, who have their hands full in practice against Rob Gronkowski (when he’s healthy), just wrapped up two joint sessions and a walkthrough against the Eagles.

Ertz did some of his best work the past three days, especially Thursday, and the Patriots took notice.

“He’s a good player. He’s a great player,” defensive end/outside linebacker Chandler Jones, a 2012 first-round pick, said. “He’s very athletic. He’s faster than I thought. I feel like he’s more of a skill player than anything. He runs his routes very well. I’ve had the opportunity to cover him for these two days of practice, and he’s been a handful.”

Ertz even shined in a rare joint walkthrough that featured a round of red-zone 7-on-7s in pads. With the second-string offense, Mark Sanchez connected with Ertz on three straight touchdowns, each tightly covered and with Ertz using his size or an elusive move to create separation.

“He’s a good tight end, an athletic guy, stretches the field,” Pro Bowl safety Devin McCourty said. “Really, I think, understands how to get open against good defenses. That’s always good work when you can go against good tight ends. They have a bunch of them. At the safety position we got some pretty good work going against them the past two days.”

Seems as if the Patriots just discovered what some national pundits are also catching onto, something Ertz’s teammates picked up on by the end of last year and early in camp.

The 2013 second-round pick, chosen 35th overall, and the highest-drafted Eagles tight end since Keith Jackson went 13th in 1988, is shedding his training wheels and kicking into higher gear.

“I hope so,” Ertz said “I’d like to think I can make an impression every day. That’s kind of my goal, to get better every day. I think I had a few good practices out here. That speaks volumes for them (the Patriots) to say that. Obviously they don’t have to say that about me, but I feel the same way about them. I think we had some good battles this week.”

Ertz’s breakthrough comes at an opportune time. DeSean Jackson and Jason Avant have been exiled and the team’s top two wide receivers, Jeremy Maclin and Riley Cooper, haven’t stayed healthy so far in camp.

The strength of the offense right now, and perhaps for the Sept. 7 season opener against Jacksonville, is the team’s deep class of tight ends, starting with Ertz and Brent Celek.

Ertz spent extra hours this offseason fine-tuning his blocking to be ready for an expanded role in Chip Kelly’s new offense. Separation isn’t really a question, which he showed again on the practice fields next to Gillette Stadium.

Ertz said he learned over the past few days that “I can make plays.”

“I pride myself on being able to create mismatches," he said. "That’s what I’ve done my whole life. My opinion is I can get open against anybody. I think to be successful in this league you have to have that confidence … I have to have that mentality that I can get open. At the end of last year I started to build my confidence back in myself, where like it was in college that I can beat anybody.”

Ertz played in all 17 games last year and finished with 36 catches (fifth-most on the team) for 469 yards (fourth-most) and four touchdowns, but he didn’t start to see significant playing time until late October.

As the calendar turned, his production picked up. His one-handed touchdown grab from Nick Foles in a road loss to the Vikings gave his coaches and teammates something positive to glean from an embarrassing 18-point defeat. His 3-yard touchdown catch against the Saints in the playoffs could have been the game-winner if the Eagles had stopped Darren Sproles from breaking open the ensuing kickoff.

Ertz’s four catches for 60 yards in the preseason opener, including a really smooth 34-yard catch from Sanchez down the seam, led the offense. Since then, Ertz has noticed his name come up in the national media as an emerging star.

He’s well aware of the recent attention and he’s not stiff-arming the speculation.

“It’s positive that there are positive things being said about me, but at the same time if I go out and have a few drops like I did in the last training camp everybody said I had bad hands, too,” he said. “So it goes both ways.

“I compare myself where I was this time last year when we were having joint practices and I was getting my clock cleaned a few times,” he said. “(Former Pats safety) Adrian Wilson jammed me badly. It was good for me to be on the other side of that. I’ve improved greatly and it’s good to see all the hard work has paid off.”